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rtc(HW)


rtc -- real-time clock interface

Description

The rtc driver supports the real-time clock chip, allowing it to be set with the correct local time and allowing the time to be read from the chip.

The following ioctl calls are supported.


RTCRTIME
This call is used to read the local time from the real-time clock chip. The argument to the ioctl(S) is the address of a buffer of RTC_NREG unsigned characters (RTC_NREG is defined as <sys/rtc.h>). The ioctl will fill in the buffer with the contents of the chip registers. Currently, RTC_NREG is 14, and the meanings of the byte registers are as follows:


0
Seconds

1
Second alarm

2
Minutes

3
Minute alarm

4
Hours

5
Hour alarm

6
Day of week

7
Date of month

8
Month

9
Year within century. Values in the range 69-99 refer to years in the twentieth century (1969 to 1999 inclusive); values in the range 00-68 refer to years in the twenty-first century (2000 to 2068 inclusive).

A
Status register A

B
Status register B

C
Status register C

D
Status register D

For further information on the functions of these registers, see your hardware technical reference manual.


RTCSTIME
This call is used to set the time into the real-time clock chip. The argument to the ioctl is the address of a buffer of RTC_NREGP unsigned characters (RTC_NREGP as defined in <sys/rtc.h>). These bytes should be the desired chip register contents. Currently, RTC_NREGP is 10, representing registers 0-9 as shown above. Note that only the superuser may open the real-time clock device for writing and that the RTCSTIME ioctl will fail for any other than the superuser.

Files

/dev/rtc
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003